1. Field of the Invention
The invention disclosed herein relates to the field of arranging interactive elements on a tape head configured to read electronic data stored on tape media.
2. Background Art
Tape heads that are configured to read electronic data stored on tape media, for example, magnetic tapes, are known. Magnetic tape conventionally include a plurality of servo tracks and a plurality of data zones. The data zones are arranged longitudinally along the magnetic tape. The servo tracks are also arranged longitudinally on the magnetic tape and bound the data zones. For example, a conventional tape may include two data zones and three servo tracks, a first and a third servo track being laterally spaced apart along the magnetic tape with the two data zones disposed between the first and third servo tracks. The second servo track is disposed along the center of the magnetic tape separating the two data zones.
A conventional tape head includes a plurality of servo track sensors and a plurality of interactive elements. The interactive elements comprise read elements and write elements which respectively read data from, and write data to, the magnetic tape as the magnetic tape passes over the tape head. The interactive elements are disposed along an engagement surface of the tape head that is configured to engage the magnetic tape as the magnetic tape passes over the tape head. The interactive elements are disposed on the engagement surface between outer lying servo track sensors. The servo track sensors are spaced apart by a distance that corresponds to the distance between two consecutive servo tracks on the magnetic tape. The interactive elements are disposed between the servo track sensors and are spaced apart from one another by a substantially equal distance.
As the magnetic tape passes over the engagement surface of the tape head, the interactive elements can read data from, and write data to, the magnetic tape. As the magnetic tape moves past the tape head, it has a tendency to stray from a constant position in a lateral direction. The servo track sensors on the tape head detect the position of the servo tracks and, hence, detect lateral movement of the magnetic tape. The servo track sensors provide feedback to mechanisms that reposition the tape head to ensure that the interactive elements maintain a substantially constant lateral position with respect to the magnetic tape. In this manner, data tracks are deposited along the surface of the magnetic tape by the write elements at precisely known lateral position with respect to the servo tracks.
A conventional tape head includes two arrays of interactive elements longitudinally spaced apart from one another. Each array typically includes sixteen read/write pairs (only eight have been depicted for ease of illustration). Each read/write pair consists of a single read element and a single write element. The read and write elements in a single read/write pair are disposed on the tape head at substantially the same lateral position along the engagement surface. Each of the read elements in an array are aligned in a lateral column with each other. Similarly, each of the write elements within an array are laterally aligned in a column with one another and also substantially longitudinally aligned with their corresponding read elements. The longitudinal alignment of the read elements with the write elements of each read/write pair ensures the proper alignment of each read element and each write element with the data tracks on the magnetic tape. Further, the read/write pairs of each array are also longitudinally aligned with the read/write pairs of the other arrays. This arrangement permits the write elements of a first array to write data to the magnetic tape as it passes over the engagement surface and a corresponding read element from an adjacent second array to confirm that the data was written correctly as the magnetic tape passes downstream to the second array. The tape head can write and confirm data in the data tracks on the magnetic tape as the magnetic tape moves past the tape head in either a forward or reverse direction.
The tape head can move laterally to the second data zone. Once the tape head is positioned over the second data zone, the servo track sensors can detect the position of the second and third servo tracks and use them in the same manner that it detected and used the first and second servo tracks. Typically, the tape head will write data to the magnetic tape in one of the data zones as the magnetic tape moves in the forward direction. Then the tape head moves to the other data zone and writes to that data zone as the tape moves in the reverse direction.
The above described configuration can present some problems. First, the tape head needs to be capable of both very fine lateral adjustments as the magnetic tape moves past the engagement surface, and also very coarse adjustments as the tape head moves between data zones. The fine adjustments require the use of very flexible electric connectors because of the very high frequency of tape head adjustments and because of the very small dimensions of such adjustments (as small as 0.1 microns). However, as the tape head moves between data zones, it travels a distance of thousands of microns. Such long distance travel requires a far more robust electrical connection because of the increased wear and tear such motion causes. The goal of providing flexible electrical connectors needed for fine adjustment is antithetical to the goal of providing robust electrical connectors needed for coarse adjustment.
Another problem encountered by the configuration described above is that the magnetic tape, which is frequently comprised of a plastic substrate, is sensitive to changes in temperature and humidity. The dimensions of the substrate change in both the longitudinal and lateral directions as the plastic substrate expands and contracts thereby making it difficult for a tape head to properly align with the data tracks. Potential solutions to this problem include doubling the number of read/write pairs within a single data zone, or, alternatively positioning the same number of read/write pairs on only half of the engagement surface. Either solution would diminish the distance between read/write pairs which in turn, places the data tracks closer together. A reduction in distance between data tracks reduces the impact on the tape head of the expanding and contracting substrate. However, because of the complexity associated with manufacturing tape heads, simply doubling or otherwise increasing the number of read/write pairs between servo track sensors is problematic and undesirable. Also, positioning read/write pairs on only half of the engagement surface would render such a tape head incompatible with previously recorded magnetic tape on which data was recorded using a conventional tape head. The present invention addresses these and other problems.